This invention relates generally to crop harvesting and threshing machines, more commonly known as combines, and more particularly to the type of machine commonly referred to as an axial flow type of combine wherein the crop material passes axially through an elongate casing and about the threshing and separating rotor contained therein. More particularly, the invention is concerned with improved crop material guide means to prevent crop material from moving initially upwardly toward the top of the casing to help prevent its wrapping on the front shaft of the rotor adjacent the material infeed area of the casing. Specifically, the guide means comprises an elongate stripper plate attached to the outer sidewall of the casing which is tapered to cooperatively interact with auger flighting mounted to the front of the rotor to guide the crop material as just described. This invention is equally applicable to an axial flow type of combine utilizing either a single threshing and separating rotor or multiple threshing and separating rotors.
The conventional type of combines previously used pass the crop material to be threshed between a rotary cylinder and a stationary concave in a direction that is normal to the axis of the rotating cylinder and parallel with the longitudinal axis of the combine frame. In this system much of the grain contained in the crop material fed to the cylinder and the concave passes through the concave as threshed grain. The remainder of the material is conveyed to separating elements of the combine that traditionally include reciprocating or oscillating straw walkers, grain pans, and chaffer sieves. These conventional combines suffer from the major disadvantage of having a threshing capacity that is limited by the single pass of the crop material about the threshing cylinder. Combines of the axial flow type, in contrast, utilize single or dual threshing and separating rotors that permit the crop material to pass over the concave during the threshing process three or more times. The rotors may be mounted either parallel or transverse to the longitudinal axis of the combine. This increased exposure to either the transversely or longitudinally mounted rotors during the threshing process permits these axial flow type of combines to increase the amount of threshed grain obtained from any crop passed therethrough when compared with conventional combines.
A feeder housing elevator on the front of the axial flow type of combine delivers the cut crop material to the front or infeed end of the threshing and separating rotors. In one variation of the type of combine in which the instant invention can be utilized there are two rotors of generally cylindrical configuration which have a short infeed auger with flightings mounted to each of their forward ends. The rotors turn in opposite directions in parallel generally cylindrical housings or casings within a combined rotor casing and have separate threshing and separating portions. The threshing portion of each rotor or threshing cylinder has as many as four rasp bars fastened thereto in closely mounted pairs. Open type of concaves are individually adjustable and sit beneath each rotor within the casing. The separating portion of the rotors have separator blades fixed to each of the two rotors to continue separating the grain from the crop material as the material moves rearwardly. The rearward movement of the crop material is aided by arcuate fins fixed to the upper portions of the rotor casing. At the rear of the rotors crop material is deflected into a transverse discharge beater and an auxiliary separating area which serve to remove the remaining grain and expel the crop material residue at the rear of the combine. These features are all shown in greater detail in prior U.S. Pat. Nos. 3,626,472, issued Dec. 7, 1971, and 3,742,686, issued July 3, 1973, both to Rowland-Hill.
When axial flow type of combines are used in certain long stemmed leguminous or grassy crops, such as windrowed perennial or annual rye grass, clover and bent grass, there is the potential for the crop material to wrap about the shafts on the front of the threshing and separating rotors, especially when the stems are tough. These long stems are characteristically tough in the early morning until the sun has had ample opportunity to dry out the moisture which accumulates overnight. Should such crop material pass over the tops of these rotor shafts, it could become tightly wrapped about the shafts so as to impair the operational characteristics of the overall machine. This operational impairment from the wrapping potentially could cause eventual damage to the operating components of the rotors by breaking the seals to the rotor bearings, cause engine stallouts by binding the rotors so tightly that they cannot run, or, at the least, prove to be extremely difficult to untwine or disentangle.
Prior axial flow type of combines have recognized the problem that this wrapping can cause. One approach which has been taken to solve this problem involves the use of a casting that surrounds the rotor shaft and serves as a bearing housing as well as a shield for the bearing. The casting forms a central hub from which a shed bar projects radially outwardly in the form of a lobe to guide the crop material outwardly from the rotor shaft. The inherent disadvantages of this design include the relatively massive size of the shed bar, the relatively high cost of the casting and the associated shed bar and the fact that this casting/shed bar combination has the potential to build up a substantial amount of heat under tough crop conditions due to its size and the constant frictional contact of the crop material with it.
The foregoing problems are solved in the design of the machine comprising the present invention by preventing the crop material from moving initially upwardly toward the top of the casing and concurrently guiding it rearwardly to thereby prevent the crop material from passing over the top of the rotor shaft and wrapping thereabout.